Thanks Yusufbek! That is a naming convention that comes from the Serverless translation of the YAML file into a real resource.

If you see the the YAML file I created a "resizer" function

functions:

resizer:

handler: handler.resizer

environment:

BUCKET_NAME: ${self:custom.bucketName}

That function is translated into "ResizerLambdaFunction" from Serverless :)