>>47862325When you appraise a Pokemon (examine your Pokemon, click the button on the bottom right, and hit Appraise), you get to see its IVs indicated by a series of bars. The better the overall IVs, the higher the star rating.
0 stars is trash
1 stars is meh
2 stars is decent
3 stars is good
4 stars is perfect (perfect IVs in all stats)
Pic related is a few examples.