Everyone can see how much bitcoin or ethereum an address has, but only you know which address belongs to you. You can however, share your address with others. It's useful to think of a bitcoin address like an email address or a bank account number.
Like with any technological advancements and/or financial products, we strongly advise that you do some research before any form of adoption in order to prevent any potential losses. Please also do a thorough check before you process any transaction