I will travel from Sacramento to Prague via Los Angeles and Paris with a single airticket from Delta. Do I need to take my luggage in LA and recheck or I'll give my luggage in Sacramento and get in Prague?
Providing this is on a single ticket, you will check in your luggage in Sacramento and pick it up in Prague. When you check your luggage in, you will see the final destination printed on the luggage tag, which will be PRG.
On the return, assuming you're following the same route, you will need to pick up your luggage in LA and carry to the transfer belt after going through customs.