Exegesis:

amēn legō humin ‘truly I say to you,’ cf. on 3.8 and 4.24.

hos an mē dexētai tēn basileian tou theou hōs paidion ‘whoever does not accept the kingdom of God like a child,’ elaborating the thought implied in the preceding clause. The phrase ‘to accept the kingdom of God’ is best understood as ‘to accept God’s rule over men.’

ou mē eiselthē eis autēn ‘shall not enter it.’ For ou mē cf. on 1.15. To enter the kingdom of God means to share in its blessings at the final consummation.

Translation:

Truly, I say to you, cf. the references on 4.24.

Whoever does not receive … shall not enter may, again, better be rendered as an ‘if’ clause (cf. on 9.24), and/or as a positive sentence, e.g. ‘only people who receive … will enter.’

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.