Why distant star's light can reach us?

When scientists do computer modeling or simulation of the Big Bang, it starts with an explosion of a singularity point, won't that modeling will end up with a Sphere?
No. The Big Bang was not an explosion in space, but an explosion of space. It happened everywhere at once, including right where you are now. There is no "centre" to the universe.
Explosion of space? So you can imagine a 3D axis coordinate? Right?
The cross section of X-Y-Z is the singularity?

Don't imagine an explosion propagating outwards from a central point.

Instead, visualise the expansion as like a baked loaf of raisin bread expanding. All the raisins move away from each other as the loaf expands. (The difference between this analogy and space, of course, is that the loaf of bread has a centre, while the universe does not, but the expansion works in a similar way.)
The universe is 93b light-year wide?
How to measure that?
The observable universe is. But it doesn't look that big to us. What we see now is the light that left distant galaxies billions of years ago, But since that light left, the universe has expanded.
There is a method called the Cosmic Ladder. It basically works like this. You have methods that can measure closer distances. These overlap with methods that can measure further distances, which in turn overlap with methods for measuring even further distances... We can use this to measure how big the universe looks to us now, take into account that this is old information, and extrapolate how much things have expanded in the time it took the light from these distant galaxies to reach us.
However, we really have no idea how big the universe truly is, the observable universe could be just a small piece of it.

But, that doesn't mean that we can just build better and and better telescopes and keep expanding the size of the observable universe forever. There is still the fact that as we look further and further away, we are looking at at younger and younger galaxies. Look far enough and you see things as they were before galaxies formed. Look even further, and you reach the time when the universe itself was opaque to light. We've then reached the limit as to what telescopes can reach.
We build these better telescopes so that we can see closer to this limit, and thus get a better idea of the what the early universe was like, and to get better data on the universe as a whole.
1. Theory says the universe is expanding faster than light's speed.
2. If (1) is true, why we can see stars ten of billions years away? (universe life 13.8 billion years)
I assume the star's light is not able to reach us because the space between them and us are getting wider faster than the speed of light..
3. How do we know the universe is 13.8 billion years old? How to measure it?
Twice light speed and I sat in dwfewf for all the things I’ve ✅ for
I think you're probably confusing an analogy that is sometimes used to describe how the universe expands with the actual shape of the universe.

The universe seems to be infinite in size, as far as we can tell. Therefore, it doesn't have any particular shape. We can't see the universe from the outside.

Spacetime as a whole is very close to being "flat" (in the technical sense of spacetime curvature). This means the universe is "open", in that if you keep travelling in one direction you'll never come back to where you started. If spacetime was spherical, then in principle you could effectively "complete the loop" and find yourself back where you started after travelling in the same direction (similar to how you can travel around the equator of the Earth in one direction and find yourself back where you started).

We can't. At least, not all at once. Our solar system is about 2/3 of the way out from the centre of our galaxy, so we see many more stars when we look towards the centre (which is in the direction of the Sagittarius constellation) compared to when we look outwards towards the edge.

No. You're seeing a view of the galaxy "side on", looking from where we are towards the centre.

Right. Same with our galaxy.