Topic: Model layer data mapping

I was following a recipe and came across something I haven't seen before. A model has an attribute called operation and in the model file it has a declaration of:

key: :value
key: :value

is this build into rails where any setting or getting of the the table will first be mapped by this and if so what is this called because I tried googling rails model data mappings and it came up with some articles on relations.

Thank you