This is the 17611th most frequent Russian word.
тыкву
"Тыкву" means "pumpkin" in English.
Here, 'тыкву' is used as a direct object in the accusative case, referring to the item bought.
Мы купили свежую тыкву на рынке.
We bought a fresh pumpkin at the market.
In this sentence, 'тыкву' is again in the accusative case, indicating what is being cooked.
Осенью всегда приятно готовить тыкву.
In autumn, it's always nice to cook pumpkin.
'Тыкву' is used in the accusative case, describing the pumpkin being cut.