Important terms that you need to know in order to understand the output from Fragstats:

• What is a landscape?
• Classes of landscape pattern:
  • spatial point patterns
  • linear network patterns
  • surface patterns
  • categorical map patterns
• Patch--Corridor--Matrix model
• The importance of scale
• Landscape context
• Perspectives on categorical map patterns:
  • island biogeographic model
  • landscape mosaic model
• Levels of landscape metrics :
  • patch-level metrics
  • class-level metrics
  • landscape-level metrics
• Landscape metrics :
  • composition:
• proportional abundance of each class
• richness
• evenness
• diversity
• spatial configuration:
• patch size distribution and density
• patch shape complexity
• core area
• isolation / proximity
• contrast
• dispersion
• contagion and interspersion
• subdivision
• connectivity
• Structural versus functional metrics

All of these terms are explained in the Fragstats Conceptual Background document provided in the Fragstats Help file.