Read for comprehension:
A recurring motif in metabolism is the formation of a Schiff' base (imine) between an aldehyde or ketone substrate and a lysine residue of an enzyme. In aldolase, for example, such a (protonated) Schiff' base stabilizes the formation of an enolate anion of dihydroxyacetone phosphate to undergo aldol condensation with glyceraldehyde 3-phosphate, or the reverse process in glycolysis (cleavage of fructose 1,6-bisphosphate). Another example is the Schiff' base formed between pyridoxal phosphate (PLP), a derivative of vitamin B6, and the lysine residues of several enzymes. PLP contains an aldehyde moeity that ideal for Schiff' base formation. The Schiff' base formed can act as an acid-base catalyst in a context which excludes water in some types of enzyme activity, or with aminotransferases, the PLP enzymes form Schiff-base intermediates with their substrates. The Schiff' base destabilizes the molecule leaving it open for decarboxylation, deamination, racemization, aldol cleavage (α carbon), elimination, or substitution (β carbon). The protonated form of PLP reduces the energy of negative charge that are involved with the catalytic intermediates in these reactions. The ring inductively attracts electrons in the amino acid substrate.
Don't let dense nomenclature push you out of comprehension. Just slow down and unpack it. If you know a bit about what lysine looks like, and you know what an imine is (Schiff's base), you can understand this.