The F major scale starts on the G note, so using the previous sequence results in the following notes.
In order for the tone and semitone pattern to be maintained, the fourth note of the F major scale must be flattened to become B flat.
Play the G major scale, and the F major scale shown, and you will notice that they both have the familiar sound of Do Re Mi Fa So La Ti Do. Remember that all major scales have this sound.