Questions & Answers about Мы гуляли по тихой аллее в парке вечером.
Гуляли is the past tense plural form of гулять.
In this sentence, гулять means something like:
- to walk
- to stroll
- to take a walk
- to spend time walking around
It is not as goal-focused as verbs like идти (to be going, walking in one direction).
So Мы гуляли suggests we were out walking / we took a walk / we were strolling.
Because the subject is мы (we), the verb must be plural: гуляли.
The form гуляли is the past tense of гулять.
Russian past tense is formed from the infinitive stem plus endings that show gender/number:
- гулял = he walked
- гуляла = she walked
- гуляло = it walked
- гуляли = they / we walked
Since the subject is мы (we), Russian uses the plural past form гуляли.