"To type a message" means to use a keyboard to write and send a written communication, usually through digital platforms like emails, chats, or text messages. Full definition
You just type a message on the instant messenger or email so you don't confront with this issue when looking for a date online. (afreedating.com)
A small message box appears in the lower right - hand corner of your browser window; type your message in the box on the bottom and hit Enter when you're finished. (lawyerist.com)
At all costs, avoid the «hi, how are you» type message as you won't hear back from them for sure. (flirthut.com)