Que means What and Cual means which.

que means ‘what’
cual means ‘which’

“Que” means “who, that, which”
“¿Qué?” means “what?”
“(el) Cual” means “as, such as, who, whom”
“¿Cuál?” means “which?”

The above answers are all correct. Just to clarify:

Qué = what?
que = that

cuál = which?
cual = which

That’s a great starting point. And if you are just starting out, you can stop reading here. If you want to think about the subtlies of usage, read on.

Let’s move on to actual usage differences.

As in English, “Cuál” asks for you to specify from a finite set of possibilities. Let’s imagine you are staring at a rack of 7 bikes:

“Which is your bike?”
“Cuál es tu bici?”

That’s pretty straight forward. But in many Spanish-speaking countries, they use CUAL (which) in situations where WE would not.

For example, in Latina America, people don’t ask you “Qué es tu nombre?” or “Como te llamas?”

They would ask you “Cuál es tu nombre?”—as if your name is from a finite set of possibilities.

Another example: “Cuál es tu numero telefonico?” (Which is your phone number? Actually, your number DOES come from a finite list.)

If you want to sound natural, this is something you will have to learn simply by listening to people speak.

It’s kinda hard to list ALL the situations in which Spanish speakers would use “cual” instead of “que”.