Let’s take a look at the meaning of the phrase “Shabbat Shalom.”

“Remember the Shabbat to keep it holy. You can work during the six weekdays and do all your tasks. But Shabbat is the Shabbat to G-d your Lord. Do not do anything that constitutes work… It was during the six weekdays that G-d made the heaven, the earth, the sea, and all that is in them, but he rested on the Shabbat. G-d therefore blessed the Shabbat day and made it holy.”
Shmot (Exodus) 20:8-11

Basically, Shabbot Shalom means Peaceful Sabbath.

When someone wishes you a “Shabbat Shalom” they are hoping you enjoy your day off.