can someone give me explanation about this

DESIGN FAILURE MODE AND EFFECT ANALYSIS
Design FMEA (DFMEA) covers the possibility of product failure and a decrease in its useful life.

and explain this following reason

These are due to the following reasons:
• Quality and properties of raw materials, components, and subcomponents.
• Geometry/design and shape of the product.
• Limits and tolerances given in the product.
• Alignment with other components subcomponents, assembly, systems, or subsystems.
• Environmental causes.