There are many parts of the body to work out, if you’re weight training, splitting what bits you work means you can do shorter and more intense workouts, a simple split would be lower one day and upper the next, rest and then repeat, but you can split into smaller body groups over more days. It depends on the time you have – better all in one go (then do a full body session), or 20 minutes a day (focus on one part each day). The other benefit to split training is DOMS – if one part is sore and needs rest, you can work another part.
Just remember to put in some rest days – overtraining could set you back.