User properties are attributes that describe groups of your user base, such as their language preferences or geographic locations. You can use user properties to define audiences.
For example, you can set a user property called favorite_food, which you can use to record each user's favorite food. You can use the data to segment users by their favorite food.
To view subtitles in your language, turn on YouTube captions. Select the Settings icon at the top right corner of the video player, select "Captions," and then specify your language.
To report on the data you collect through user properties, create user-scoped custom dimensions. Google Analytics defines some user-scoped dimensions (e.g., Age and Language) for frequently defined user properties.