The tables give the normals for maximum and minimum temperatures based on weather data collected from 1981 to 2010 by the US National Climatic Data Center. You can jump to a separate table for each region of the state: Eastern Shore, Central Maryland and Western Maryland.
A computer application is simply another word for a computer program or an executable file. Examples would be games, word processors (such as Microsoft Word), and media players.
Unlike system software, an application program (often just called an application or app) performs a particular function for the user. Examples (among many possibilities) include browsers, email clients, word processors and spreadsheets.