Jamieson, Fausset and Brown on Zechariah 2:4

4. this young man--So Zechariah is called as being still a youth when prophetically inspired [Grotius]. Or, he is so called in respect to his ministry or service (compare Nu 11:27; Jos 1:1) [Vatablus]. Naturally the "angel that talked with" Zechariah is desired to "speak to" him the further communications to be made from the Divine Being.

towns without walls for the multitude ... Cattle--So many shall be its inhabitants that all could not be contained within the walls, but shall spread out in the open country around (Es 9:19); and so secure shall they be as not to need to shelter themselves and their cattle behind walls. So hereafter Judea is to be "the land of unwalled villages" (Eze 38:11). Spiritually, now the Church has extended herself beyond the walls (Ep 2:14, 15) of Mosaic ordinances and has spread from cities to country villages, whose inhabitants gave their Latin name (pagani) to pagans, as being the last in parting with heathenism.