Lets Say, you have a cloth tied at for ends such that the cloth is straight.

When you put a heavy object at the center, say, a solid ball🏀, you'll observe that the cloths becomes bent towards the object and any significantly lighter object🎾 runs towards the ball.
This is how gravity works.
Unlike your cloth and a ball which is only in one direction, in spacetime, it's bent in all directions, everything less less massive in all directions falls in.

Now, that you're familiar with the fabric and the ball, you'll observe that if you shove the ball🎾 a little, it moves away from the🏀 but eventually comes back that's the effect of gravity on it and it falls back with a constant acceleration.
Now if you shove the 🎾 with enough force it's reaches a speed which grants it freedom off the fabric. That's what is called an escape velocity.

Now, take a very large and strong cloth, this large🗾 with a very massive object say a🏟 and your still small ball.
🎾
You'll notice, that at points closer to the edge of your fabric, the ball can always escape, but as you move closer to your 🏟, the ball seems not to escape but always comes back, that point is called and event horizon and the 🏟 is the black hole.