What are these pest?

[Blackpepper]

I took a picture of back of the leaf.
Almost all leaves have these.
Ever since having these,Leaves are curly and fruit are very small.

What is the best thing to so to get rid of this.

Thank you.

 

[dlsolo]

You've got aphids... soapy water, ladybugs (or ladybug larvae), soap and neem oil, or spraying our plant down with a garden hose...
 
Many different ways in handling aphids.  https://www.almanac.com/pest/aphids