1.25l Fiestas are hydraulic clutch using a concentric slave cylinder. You can't see it; it's inside the bellhousing. Failure is common, with the posted symptoms. If you look under the car at the bellhousing/engine joint it might be possible to see the the brake fluid leaking out. If that's the case, and it porbably is, it's fearbox off and new clutch time. it is not worth replacing just the cylinder whilst you're in there. Nor is worth replacing the clutch without doing the cylinder at the same time.
Concentric cylinders are not the good idea they appeared to be. They are no more reliable than an externa; cylinder, but are a much bigger job to fix.
If the car is the model of Fiesta that's recently been replaced, it might just be that the pushrod between the master cylinder and the pedal has come loose. That's not attached to the pin on the pedal, and is another common fault. There should have been a clip, circlip, split pun or at least something to hold it in place.