What is this symbol near an AC motor?

The capacitor symbol inside it may be a clue; the block next to it is one way of representing a resistor, and the staggered lines above it suggest there are three.

Given this, I suspect it's three R-C snubbers, wired in delta, to reduce noise and switching transients on the 3 phase supply. This IS a guess, but there's not much else it could be.

Component values? Resistors in the tens of ohms, capacitors a fraction of a microfarad (e.g. 47R,0.1uF) would be typical. The physical unit is probably a sealed metal can, and may or may not have such useful information printed on it.

Given that it is on a 3 phase motor, I'd say it is a set of Power factor Correction capacitors, which typically come with discharge resistors. The graphic is likely a lazy way of depicting it, this is the more complete version:

Or the image is a copy of a copy of a copy, and some of the lines have been lost.

Boy, that looks like a 3-phase power line filter/conditioner.