Passage
And they understood not the saying which he spake unto them.
And they understood not the saying which he spake unto them.
Luke 2:48 And when they saw him, they were amazed: and his mother said unto him, Son, why hast thou thus dealt with us? behold, thy father and I have sought thee sorrowing.
Luke 2:49 And he said unto them, How is it that ye sought me? wist ye not that I must be about my Father’s business?
Luke 2:50 And they understood not the saying which he spake unto them.
Luke 2:51 And he went down with them, and came to Nazareth, and was subject unto them: but his mother kept all these sayings in her heart.
Luke 2:52 And Jesus increased in wisdom and stature, and in favour with God and man.
The verse centers on "understood", "saying", and "spake". It is saying that the verse draws attention to "understood" and "saying", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 49's "And he said unto them How is..." into verse 51's "And he went down with them and...", so "understood" and "saying" belong inside that flow. In Luke context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "understood" and "saying" with trust shaped by these words, not by a vague optimism outside the passage.