Input Bias Current in an OP-AMP and its value in a datasheet
Bias current is the typical/max current that can be assumed to flow at both input terminals.

Offset current is the typical/max difference in the bias currents.

When multiplied by any series resistor on inputs, bias current gives you the typical/max voltage that each input might settle to due to its bias current.

If an opamp has a large resistor between output and -ve input, and the same value resistor from ground to +ve input to compensate, then the offset current times that resistor value gives you the typical/max output voltage to expect from the imbalance in bias currents.