The main benefit of joining a credit union and putting your money into a credit union instead of a regular bank is that with a credit union you pay lower fees and get a higher interest rate on your savings accounts with a credit union.
A credit union is a non profit bank while a regular bank is a for profit and makes profit off of the customers deposits where they send the money off to invest and loan out where they earn interest on your money.
A credit union can sometimes be better for you than a regular bank account.
If you want a good high yield savings account where you earn a lot more interest and money on your savings then a credit union would usually be the type of bank to go with.