Logo padding, more formally called clear space, is the minimum buffer of empty space required around a logo whenever it's used — keeping other text, graphics or the edge of a layout from crowding it.
Clear space is typically defined relative to a measurement within the logo itself (like the height of a specific letter), so it scales proportionally no matter what size the logo is used at.
This rule should be documented explicitly in a brand style guide — without it, the logo is likely to get crammed into tight layouts over time, undermining the polished impression it was designed to create.