Its posible to make a bank (To save/withdraw mony), and how to make it?

Yes. Things you'll need to consider:

• How the player will use this bank (the interface) - this includes both how (and when) you want to display the information and how you want the player to be able to interact with it.
• How the server needs to respond to each of the things you want to let the player do
• How the server can save and remember money in between visits (if this is something you want to do).

The answers to these questions can get you into very different areas of scripting.

Topics you may need to learn about:

• Guis (SurfaceGui or ScreenGui)
• UserInputService (this is one option for receiving user input - you can also just use the guis)
• RemoteEvents/RemoteFunctions (for telling the server what the player wants to do)
• DataStoreService (if you want to save a player's money for when they return to the game)
• Real mathematical formulas (if you want to deal with simulating interest)
• Tables (to keep track of information for each player - alternatively you can use leaderboards/Intvalues/NumberValues to store the information)

Your main resource for learning how Roblox works: https://developer.roblox.com/en-us/api-reference/ - you can search for any class and get details on how to use it and what it can do. Roblox sites also have a bit on how to make guis.

You can learn a bit with the Guides in Scripting Helpers: https://scriptinghelpers.org/guides

Some people also benefit from YouTube tutorials or learning from free models. If you search through free models, consider only doing so in a blank place and don't copy/paste anything without carefully exploring the entire thing - and be careful of code hidden out of view (you may need to scroll to the right considerably). Ideally you don't copy/paste anything, but simply use them as learning resources. (It's safe to run scripts from free models in a blank place to test them out or experiment with changes, since then anything they do is contained to that one place.)