[Tomisimo]

The simple present tense in Spanish is the most common way of expressing the simple present AND the present progressive in English.

Voy a la tienda - I'm going to the store.


However, you can use the present progressive in Spanish, when you're actually in the act of doing whatever it is you're doing at the moment.

Estoy comiendo - I'm eating (right now I'm actually eating).

There's also another dynamic with ir/venir that's different than English. IR is always used when the destination (yours or someone else's) is not the same as your current location, and VENIR is used when the destination (yours or someone else's) is the same as your current location

Example:

Someone knocks on the door and you call out:
I'm coming!
The destination (the door) is not the same as your current location, so you have to use ir.
¡Voy!

It´s the same with traer and llevar.