In short, one Jager is the smallest unit of a Binance Coin (BNB).
For a related example, one Satoshi is the smallest unit of a Bitcoin (BTC).
Most cryptocurrencies have the ability to be divisible up to a certain amount of decimals, as dictated within each cryptocurrencies protocol (set of rules).
Binance Coin has 18 decimals. In cryptocurrency, decimals refer to how divisible a coin or token is. Ranging from 0 (indivisible) to 18 or higher if required.
Technically speaking, the decimals are the number of digits that come after the decimal place.
1 Jager = 0.000000000000000001 BNB
The term “Jager” originated from the telegram handle of the then Binance Community Manager, Jager. Having been a Binance Angel since the launch of Binance and then a Community Manager, CZ decided on the term Jager for the smallest denomination of a Binance Coin.