How do i make an exchange system ?

Hello! I hope u have a great day. Basically, i want to know what to use so a player can put inside a textlabel a number that he wants, and with that number he gets the exactly amount of coins/whatever currency. I know is a thing implemented in roblox studio for this but i forgot what.

I found out the solve of the problem, it was the textbox , i completely forgot. I ll let the answer here for other newbie devs that doesn`t know :D