I am going little bit crazy now; what's right and what's wrong?
I don't see 7 semitones anywhere. All I see is 2 semitones in a major scale/Diatonic scale.
Look more closely at the image. On the left, there are note names; on the right, there is a diagram of a piano keyboard. With the note names, you can see that some notes are connected by lines labelled Tone; these notes correspond to the white keys on the keyboard.
However, there are also black keys on the keyboard, that correspond to in-between notes. These are labelled in lighter text. On the left side, we see
C# (pronounced "C sharp") in between the
D; this note can also be called
Db (pronounced "D flat"), with the standard system of notes we are using here. The piano keyboard diagram puts both labels on that black key.
You can also see that the E and F, and the B and (upper) C, are connected by lines labelled Semitone. This is because these notes/white keys don't have another note/black key in between them.
In English, "semi-" is a prefix meaning "half". The conceptual "distance" between the notes of a tone - i.e., "how much higher" D is than C - is twice that between the notes of a semitone (e.g. between F and E).
In the approximations that we use in teaching Western musical theory at an elementary level, we say that the note played by the G key on the piano is a perfect fifth above the C note - that is the name we use for that interval. The notes played by each key in sequence are equally spaced out: it takes 12 semitones, or 6 tones, to get from one C to the next C, an octave up. Similarly, from the C to the G we count 7 semitones: C-C#-D-D#-E-F-F#-G. (Or, using the "flat" names: C-Db-D-Eb-E-F-Gb-G.)
The reasons for all of these alternate names, for having black keys between some but not all white keys, etc. will become clear as you learn more of the theory - it would be out of scope to try to explain them here. Similarly, "perfect fifth" is actually intended to mean an interval that is very slightly larger than the distance from a piano's C to a piano's G (smaller than most people would be able to notice by listening).
There are specific reasons why we divide the octave up specifically into 12 notes, and then make these kinds of approximations, that will become clearer if you study more theory. (There's also history behind why we have the name "Tone" for the distance e.g. from C to D - i.e., two notes up in our sequence of adjacent notes.) It's also possible to do it any number of other ways. There aren't any specific "notes"; you can make sounds at any pitch want - they just won't be ones that Western musical instruments are designed to play, and won't necessarily sound good, or make sense to include in music written in Western styles, or have any natural representation in Western music notation.