In a nutshell, a Jager is a BNB's smallest unit. The majority of cryptocurrencies can be divided up into a specific number of decimals, as specified in each coin protocol (set of rules).
BNB contains 8 digits. Decimals in cryptocurrency refer to a coin's or token's degree of divisibility. Between 0 (indivisible) and 8 or higher, as necessary. In mathematical terms, decimals are the number of digits that follow the decimal point.
The telegram handle of Jager, the former Binance Community Manager, is where the word “Jager” first appeared. CZ chose the name Jager for the smallest denomination of a BNB because he has been a Binance Angel since the company's founding and later served as the community manager.