It is a very informal and friendly way of saying that something is okay or acceptable.
Here are some examples:
* "Me compré un coche nuevo." "Ta gueno, ¿de qué marca?" (I bought a new car. "It's cool, what brand is it?")
* "Vamos a la playa." "Ta gueno, ¿a qué hora?" (We're going to the beach. "It's cool, what time?")
* "Te hice un pastel." "Ta gueno, gracias." (I made you a cake. "It's cool, thanks.")
Keep in mind that "ta gueno" is very casual and might not be appropriate for formal settings.