This is the 3971st most frequent Turkish word.
cumhuriyetimizi
"Our republic."
The word 'cumhuriyetimizi' translates to 'our republic' and here it indicates possession (our) and includes a direct object form (we celebrate).
Cumhuriyetimizi her yıl büyük bir coşkuyla kutluyoruz.
We celebrate our republic with great enthusiasm every year.
In this sentence, 'cumhuriyetimizi' is used to denote the object (our republic as the entity to be protected and transmitted).
Cumhuriyetimizi korumak ve gelecek nesillere aktarmak hepimizin görevidir.
It is everyone's duty to protect our republic and pass it on to future generations.
Here, 'cumhuriyetimizi' implies that the action (strengthening) is directed towards 'our republic'.