Sergers overcast the seams. Look at a ready-made garment's seam. You'll see thread covering the edge. That is what a serger does. Be careful when you use one. It trims the fabric at the seam as it sews (it looks great but ripping and resewing is not always simple). Sergers greatest use for me was knit type materials. Wovens were harder to handle but I serge them too.
You will have to give yourself a little play time to get to know your machine before. I recommend scrap or ugly fabric to play one. Make some napkins to learn how to use the rolled hem, etc. I love my serger but I do not own this brand.