The phrase in question functions as a noun phrase. Specifically, “best” and “free” act as adjectives modifying “word games,” and “for Android” further specifies the type of games being considered. The whole phrase identifies a specific category of mobile applications.
Identifying engaging and cost-effective diversions for mobile devices is a widespread pursuit. Such digital pastimes offer accessible cognitive stimulation and entertainment. The availability of such options has broadened significantly with the proliferation of mobile devices and app stores, making them more relevant than ever.