Predictive-text input is a feature that helps a smartphone user see a list of words that closely match whatever he is typing on the keyboard and then choose the desired word without writing the whole text. The feature is useful for newcomers to the typing world but for people who are quite used to it, the predictions only eat up screen space and serve no other useful purpose. This feature is available in all Android smartphones available today and can be disabled/enabled as per requirement.
The following screenshot shows an Android compose message screen when predictive-text input is enabled.