I am able to make out the first and the last words, and my best judgment is that this is a verse from Psalms 118:26:
בָּר֣וּךְ הַ֭בָּא בְּשֵׁ֣ם יְהוָ֑ה בֵּ֝רַֽכְנוּכֶ֗ם מִבֵּ֥ית יְהוָֽה׃
Blessed be he that cometh in the name of the LORD; We bless you out of
the house of the LORD.
As mentioned, above, it is an ornament with no specific significance other than that. From what I can tell, they have abbreviated G-d's name using only the daled, so it has no "holiness" per se.
The verse is a good one, though. Perhaps, the idea is that people coming into the synagogue will easily notice this, and the words in the verse portray a theme of welcoming.
That's for the phrase in the semi-circular pattern. I'm uncertain about the phrase below it.