Plain English Meaning
There are top speeds you must stay under when flying a holding pattern. The faster you go, the bigger the pattern gets, so the rules cap your speed based on how high you are.
Full Definition
The maximum indicated airspeeds at which an aircraft is permitted to fly while in a published or assigned holding pattern. Per FAA standards, the limits are 200 KIAS for holding patterns up to and including 6,000 feet MSL, 230 KIAS for patterns above 6,000 feet up to and including 14,000 feet MSL, and 265 KIAS for patterns above 14,000 feet MSL. Certain holding patterns are charted with lower maximum speeds, and those charted limits override the standard values.
Context Anchor
Seen when flying or briefing an instrument procedure that includes a , including a hold used instead of a .