Encryption means to convert (information or data) into a cipher or code, especially to prevent unauthorized access. Another way of putting this is to just think of it as a way to conceal data in something by converting it into a code.
128 bit encryption is known to be very secure and as a matter of fact it's said to take significantly longer than the age of the universe to crack a 128-bit key.
Advanced Encryption Standard (AES), also known as a Rijndael. Is a specification for encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST). AES is a symmetric block cipher used by the U.S. government to protect classified information and is implemented in software and hardware everywhere to encrypt sensitive data.