en_tn_condensed/lev/25/54.md

If he is not redeemed by these means

"If no one redeems him by these means from the one who bought him as a slave"

by these means

"in this way"

he must serve until the year of Jubilee, he and his children with him

The Israelite slave and his children would serve the foreigner until the year of Jubilee, and then the foreigner would have to set the Israelite and his children free.