There is no dislike button on X(formerly Twitter). So when people refer to the ratio, they are referring to the likes vs. replies. A popular post may have many more likes than replies. An unpopular post may have very few likes, but a lot of replies. This indicates that many people replied to voice their disagreement.

Ratio'd means it was an unpopular post and many more people replied to it than the number of people who simply liked the post. I know, it's stupid. Kidz these dayz.