F 5/C#
The F 5 chord consists of the F (Perfect unison) and C (Perfect fifth) notes, with C# as the bass note.

How to play the F 5/C# chord
- Play C# as the lowest bass note in the left hand
- Find F (Root) on the piano keyboard
- Add C (Perfect fifth) — 7 semitones above F
- Press all 3 notes simultaneously to sound the F 5/C# chord