The "Rule of Thirds" is a popular rule-of-thumb in image composition. It encourages you to place your image's Center-of-Interest at or very near one of the points where lines cross when you divide your image frame into three parts, both horizontally and vertically.
This "Rule" is so pervasive that camera manufacturers often include such lines in the camera's viewfinder.
Like many other Cliche's this "Rule" does have a factual basis. Many pleasing images do indeed adhere to this "Rule", whether by design or by accident.
However, you should use Rules-of-Thumb to inform your creativity, not to control it.
I recommend that you learn to let your scene itself suggest how you should frame and compose it. If that process just happens to result in a "Rule-of-Thirds" composition, fine.
Like Ansel Adams, who "previsualized" is photo's final composition in the field, you should decide how you will frame, and perhaps crop, your image while you are experiencing the scene "live", rather than later - when your original intent way be weakened or forgotten.
Until next time...