What do "throttled" or "slower speeds thereafter" mean?

Cellular data is used when performing certain actions or activities on your device.

How does data work?

Cellular data is used when performing certain actions or activities on your device. This includes browsing the internet, checking email, downloading applications, streaming music, watching movies, and accessing social media apps like Facebook and Instagram.

Everything you do on your phone, that uses the internet, will come from your data plan unless you are connected to a WiFi network.

RedPocket mobile plans include unlimited talk, text, and cellular data. Certain plans have a specific amount of high-speed data and after that is used, speeds will be slower -- throttled to 512kbps. 

Despite this reduction in speed, you will still have access to the internet, allowing you to browse applications, check emails, and more.