Set the length and the character types (uppercase, lowercase, digits, symbols) and click Generate to create a random password.

The entropy (in bits) measures how many attempts would be needed: 12 characters with all four types (88 possible symbols) are about 77 bits. As a reference, from ~80 bits a random password is out of reach for brute force. It only applies to randomly generated passwords: one you choose yourself has far less than its length suggests.