Meaning of "caps not pop with watch crystal" in a schematic
The ADuC 841 integrated circuit will work with either of two alternative crystals. The ADuC 841 evaluation board (for which the schematic notes have precipitated the question) has therefore been designed to take either of those crystals. It has footprints for capacitors C17/18, which depending on which crystal is fitted can be either populated or left unpopulated.

If you fit the 11MHz one, you must also fit the capacitors.

If you fit the 32768Hz one (a 'watch' crystal) you must not fit the capacitors. Pop is an abbreviation for populate.