This is the 639th most frequent Czech word.
třetím
The Czech word "třetím" means "third" in the instrumental or locative case.
In this sentence, 'třetím' modifies 'rohu' to specify its ordinal position, using the locative case since it follows the preposition 'na'.
Na třetím rohu odbočte doprava.
Turn right at the third corner.
Here, 'třetím' is in the locative case, modifying 'patře', to indicate a specific location.
Setkali jsme se na třetím patře budovy.
We met on the third floor of the building.
The word 'třetím' is used here as the dative or locative case of the numeral 'třetí', modifying 'místě' to indicate its position in the ordinal ranking.