Passage
As a holy flock, as the flock of Jerusalem in her solemn feasts: so shall the waste cities be full of flocks of men: and they shall know that I am the Lord.
Ezekiel 36:38 (DRB)
Nearby Context
Ezekiel 36:36 And the nations, that shall be left round about you, shall know that I the Lord have built up what was destroyed, and planted what was desolate, that I the Lord have spoken and done it.
Ezekiel 36:37 Thus saith the Lord God: Moreover in this shall the house of Israel find me, that I will do it for them: I will multiply them as a flock of men,
Ezekiel 36:38 As a holy flock, as the flock of Jerusalem in her solemn feasts: so shall the waste cities be full of flocks of men: and they shall know that I am the Lord.
Study Lenses
The verse centers on "holy", "flock", "jerusalem", "solemn", "feasts", "shall", and "waste". It is saying that the verse draws attention to "holy" and "flock", so its meaning should be read from those terms before moving to application.
The prior verse says "Thus saith the Lord God Moreover in...", giving immediate footing for "holy" and "flock". In Ezekiel context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "holy" and "flock" with trust shaped by these words, not by a vague optimism outside the passage.