53 Or “disciplinarian,” “custodian,” or “guide.” According to παιδαγωγός, “the man, usu. a slave … whose duty it was to conduct a boy or youth … to and from school and to superintend his conduct gener.; he was not a ‘teacher’ (despite the present mng. of the derivative ‘pedagogue’ … When the young man became of age, the π. was no longer needed.” L&N 36.5 gives “guardian, leader, guide” here.
54 Or “be justified.”

In other versions

So then, the law was our guardian until Christ came, in order that we might be justified by faith.

So the law was our guardian until Christ came that we might be justified by faith.

The law, then, was our guardian until Christ, so that we could be justified by faith.

Let me put it another way. The law was our guardian until Christ came; it protected us until we could be made right with God through faith.

So then, the law became our guardian until Christ, in order that we could be justified by faith.

Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith.

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