This is the maximum speed the product is capable of technically achieving. Actual speed achieved may differ, depending on many factors e.g. time of day, contention ratio etc. Broadband products typically come in a range of download speeds. The higher the download speed the faster it is to open web pages, download files etc.. More sophisticated uses of broadband such as online gaming typically require higher broadband speeds.
If you are unsure what download speed you require, select "Don't Mind" and your cost comparison result will include products covering the range of download speeds available.