In my chemistry class in high school we just started with resonance and my teacher said that its the phenomenon of moving around of negative charges, lone pairs or pi electrons with no change in position of atoms and in conjugation with pi electrons. Could someone explain what the statement in bold is supposed to say?
Did you look up conjugation in the dictionary? It implies joining, but in chemistry it is joining the atoms in a special way.
The chemical meaning is straightforward, see https://goldbook.iupac.org/terms/view/C01267
In the original meaning a conjugated system is a molecular entity whose structure may be represented as a system of alternating single and multiple bonds
More explanation here Chemistry LibreTexts