When you schlep something, you lug or carry it with difficulty. If your taxi can't make it up an icy hill, you might have to schlep your groceries all the way up to your house.
If you schlep something, it's either awkward or heavy — or both. You have to pull or drag or tug things when you schlep them. You can also describe an awkward, long, or rough trip as a schlep: "It's such a schlep to get down Grandma's road during mud season." The word has a Yiddish root, shlepen, "to drag," from the Germanic sleifen, also "to drag."