What's the difference between get and take? How to choose the correct word for a specific context(Ex: I wanna get this or I wanna take this)?
Take implies removal, therefore you can successfully take something only if it's physically in front of you. For example, if you are in the kitchen, you can take a cup from a cupboard in the kitchen, but you can't take it off the table in the bedroom until you're in the bedroom.
You can get something that's not in front of you - for example, getting groceries - you might have to go to the store first. You can't take them off the shelf until you are there. (You can emphasize the fact that getting something will involve a trip with go get X).
Take and get have additional meanings and generally they do not overlap.
Get X can mean "change your state/position to X" - e.g. get away, get out, you're getting tired, she got arrested, etc. Take doesn't work like that.
Get X can mean "understand X" or "internalize X with your knowledge/intuition" - e.g. yes, I finally get what you are saying. Take doesn't work like that.
Take X can be used with a few things to mean "eat/do something nourishing/fun/refreshing/educating" - e.g. take a break, take your lunch, take the medicine, take a class. It's not common to use get this way but possible because get means "obtain" (take is more synonymous with "remove").
Both get and take have a number of phrasal overloads, e.g. take over X (conquer or assume ownership of X), take out X (kill X), get over X (stop worrying/thinking about X), get at X (annoy X), etc.