The "Strainbow" you are likely asking about is a popular hybrid cannabis strain known for its fruity flavor profile and balanced effects. It is often a blend of different strains, varying slightly by producer. 
Strain Details
Aspect Details
TypeHybrid (often a balanced 50/50 mix of indica and sativa characteristics)
THC ContentTypically ranges from 18% to 24%
Flavor ProfileNotes of sweet berries, tropical fruit, and general fruity sweetness, reminiscent of candy
Dominant TerpeneMyrcene (contributes to relaxing qualities), also contains Limonene and Pinene
Reported Effects & Benefits
Users and producers report a variety of effects which can vary by individual. 
Feelings: Users often report feeling euphoric, relaxed, creative, blissful, and uplifted. It can provide an interesting mix of being both active and relaxed simultaneously.
Potential Relief: Medical patients may use Strainbow to manage symptoms associated with:
Anxiety
Depression
Chronic pain
Stress
Appetite stimulation