The Google Play Store is one of the largest, if not the largest, stores selling apps, games and content on any smartphone, and especially on Android. Having access to Google Play greatly increases the amount of apps that are available to download to a phone, and many of these are free.
The Contixo Kids Q102 is an Android tablet, and Google Play is an Android store, but not every tablet running Android, especially amongst those designed for children, can use the Play Store. The Q102 is, however, one of the tablets that can access it, and the app comes pre-installed, so there is no worry about getting it onto the tablet.