Something that is alphanumeric has both letters and numbers in it. This frequently involves passwords or security codes. A phrase made up of alphanumeric characters might serve as the password for a cryptocurrency exchange or wallet.
In general, people consider alphanumeric phrases to be secure password selections. An account is more secure when the password is a mix of letters and numbers. The likelihood of the account being compromised decreases as the alphanumeric combination becomes more random.