Conditional sentences, generally speaking, are those with the structure if... then... There are two types: real conditional situations are likely or very probable (e.g. If he comes, I'll tell him), whereas unreal conditional sentences are hypothetical or contrary to fact (e.g. If he were to come, I'd tell him or If he had come, I would have told him).

Real Conditional: Use љсли with the appropriate verb tense.

Unreal Conditional: Use бы + л in both clauses.