Japanese uses either a “regular” keyboard with latin letters that you use to spell approximations of Japanese sounds, or something like what western phones used to use where you have 10 buttons that each allow you to select from 5 characters each by flicking. Like this The second is what most Japanese speakers use on our phones. In both cases, after typing something (usually several words) you have suggestions displayed to you that match the pronunciation of what you just typed.

With a standard keyboard as an example ka -> か -> 化

Here’s a good video you can skip around https://youtube.com/watch?v=to8QUll9_gM.