Literally, "it seems like a lie".
- it's hard to believe
- Parece mentira que tus tíos se hayan divorciado.
- It's hard to believe that your aunt and uncle have divorced.
- Parece mentira que el concierto sea divertido.
- It's hard to believe/It seems like a lie that the concert would be fun.
- Parece mentira que la cantante se haya subido una nave espacial.
- It's hard to believe/It seems like a lie that the singer has gotten on a spacecraft.
Usually used as "parece mentira que + subjunctive" because it expresses doubt.