I ... thou (egō ... su). Jesus repeats the pronouns used by Peter in similar contrast.
Not now (ouk arti). Just now arti means (Joh 9:19, Joh 9:25). Used again by Jesus (Joh 13:33) and Peter (Joh 13:37).
But thou shalt understand hereafter (gnōsēi de meta tauta). Future middle of ginōskō (instead of the verb oida) to know by experience. “Thou shalt learn after these things,” even if slowly.