Exegesis:

hotan idēte tauta ginomena ‘when you see these things happening.’ tauta takes up toutōn in v. 28 and refers to the events announced in vv. 25f.

hoti eggus estin hē basileia tou theou ‘that the kingdom of God is near,’ i.e. ‘that the coming of the kingdom of God is near.’ For hē basileia tou theou cf. on 4.43.

Translation:

So also … you know, or, “in the same way … you may be sure” (New English Bible), ‘so yourselves also … then you know’ (Sranan Tongo).

The verbs see, know and is may better be rendered as futures.

The kingdom of God is to be taken as a temporal phrase, ‘the time when God rules.’

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.