Characters in WordPress database?

I often have to deactivate all of the plugins when I am troubleshooting a site that I can’t get logged into. I usually do this with ftp, but I have read you can do it by editing the “active_plugins” field in wp_options. When I view this field I see characters such as a:8:{i:0;s:31 what do these represent? I have been told it is something MySQL related that refers to data types and their size, but I would like more info.