תַּשְׁבִּיתוּ command form: "you will cease/rest/stop": from the same root as "Sabbath"
שְּׂאֹר = "leavening agent".
מִבָּתֵּיכֶם = there are three words, well, four, in this one Hebrew word:
mem, מ, prefix is "from"
beitey, בתי, is "houses of"
khem, כם, means "yours"
Altogether: "you will cease leavening agents from your houses..."
These actions have spiritual significance; leavening, yeast or chametz have been associated with sin which grows within us.