This is the 15791st most frequent Russian word.
прогулку
"Прогулку" means "a walk" in English.
Here, 'прогулку' is used in the accusative case as the direct object of the verb 'пошли', indicating the action of going on a walk.
Мы пошли на прогулку в парк.
We went for a walk in the park.
'Прогулку' appears in the accusative case, showing the planned activity, and its context specifies a walk along the beach.
Прогулку по пляжу мы запланировали на вечер.
The walk on the beach is planned for the evening.
This usage of 'прогулку' is indicative of suggesting an action using the word in the accusative case as part of the verb phrase 'совершить прогулку'.