This is the 5541st most frequent Japanese word.
かさ
Umbrella.
傘 is used to refer to an umbrella.
この傘は新しいです。
This umbrella is new.
傘 is used in the context of necessity due to weather conditions.
雨が降っているので傘を持って行きます。
It's raining, so I'll take an umbrella with me.
傘 (specifically 日傘 here) is used for shading oneself from sunlight outside.