Respiration releases energy - it is an exothermic process.
Don't confuse respiration with photosynthesis. Photosynthesis is the process by which plants, and some bacteria, synthesise food molecules - which they then use, in addition to other things, for respiration. The process of photosynthesis requires energy - it is endothermic.
Don't confuse respiration with breathing, which is ventilation. Respiration happens in cells.
Why organisms need energy
All organisms need energy to carry out metabolic processes. This energy is used: