Walking in a slow, relaxed, and leisurely way.
“A young couple is strolling along the beach at sunset.”
“Several people are strolling through the park, enjoying the sunny weather.”
Use this word instead of the basic verb 'walking' to describe people moving calmly through a park or street scene in Task 3 — it's more precise and shows you can use varied action vocabulary, which raises your vocabulary score.
Synonyms: walking leisurely, wandering, ambling