Are you referring to secondary fermentation which is a natural part of the life cycle of the yeast and the fermentation process,
or moving your beer to a secondary vessel, for the purpose of clearing your beer..
The former is unescapable, and happens automatically, the latter has been done to death on here, and you can find all the info you need already on here. There's thousands of threads about it, and was at least 12 yesterday asking the same thing.
If you start here, then follow the links, you can make up your own mind if you want to rack to a secondary
https://www.homebrewtalk.com/f39/new-221066/#post2591728
The term you used, "Secondary fermentation" is actually a misnomer, since no fermentaion SHOULD happen in the secondary. THe secondary is to clear your beer, though many of us no longer use a secondary, but instead opt for the long primary, leaving our beers in primary to clear up, and feel that our beer is much better for it.
If you want to read more about the various ideas about secondary and no secondary and the beliefs about WHEN one should secondary, Read this and the accompanying links in the article, and then you can make up your own mind as to what to do.
https://www.homebrewtalk.com/f39/multiple-questions-about-secondary-fermentation-140978/#post1601829