συντελείᾳ τοῦ αἰῶνος

The Greek phrase συντελείᾳ τοῦ αἰῶνος contains two central words, with the word τοῦ - meaning "of" - in between.

The Greek word συντέλεια (synteleia) means the end - referring to the end of something, according to Thayer's lexicon.

The Greek word αἰών (aiōn) means “age” or “perpetuity of time” or “period of time” according to the lexicon. This relates to ones time on the earth – an era or lifetime.

Jesus is speaking of the time of death – when the physical body dies - the end of this lifetime.