This is the 1975th most frequent French word.
tortues
Turtles.
The word 'tortues' represents the subject of the sentence, referring to the animal turtles in general terms.
Les tortues se déplacent lentement.
Turtles move slowly.
The word 'tortues' is used here to denote the specific countable items (turtles) observed in a particular location.
Il y avait plusieurs tortues sur la plage.
There were several turtles on the beach.
'Tortues' is utilized generally again in this statement to denote the species being observed.