When used as a suffix, the modern colloquial idiom -ish indicates, "approximately".
Example: Dave: "So when should I pick you up to go to the movie?" Melissa: "Eight-ish. It only starts at 8:30."
In this example, the meaning is "sometime around eight o'clock". It can be 8:05, even 8:10; Melissa lives only a few minutes' drive away from the movie theater. Dave does not need to arrive "on the dot" (exactly at 8:00 PM). However, he should still arrive at a time relatively close to 8:00.
This could also be written "8-ish"; it is not likely to ever be accepted in formal written English. It is colloquial, and widely understood by native speakers (at least in North America), and should always be used appropriately to indicate an inexact, approximate quantity.