Typically, limits of multisorted algebraic theories (by which I mean a pair of a set $S$ and an $S$-sorted algebraic theory $\mathbb F(S) \to L$) are most easily described in terms of their presentation as categories with finite products (i.e. a cartesian (monoidal) category), whereas colimits are most easily described in terms of their presentation as equational presentations, i.e. by sets of operations and equations.

- The limit of a diagram of multisorted algebraic theories is given by the limit of the underlying cartesian categories. This means, for instance, that the product of an $S$-sorted algebraic theory with an $S'$-sorted algebraic theory will be an $(S \times S')$-sorted algebraic theory. When $S = S' = 1$, this recovers the product of one-sorted algebraic theories, since $1 \times 1 \cong 1$. Limits of algebraic theories typically do not have nice descriptions in terms of the operations and equations (e.g. the product of two finitely presented algebraic theories will not usually be finitely presented).
- Take a morphism of multisorted algebraic theories, from an $S$-sorted algebraic theory $\mathbb F(S) \to L$ to an $S'$-sorted algebraic theory $\mathbb F(S') \to L'$, to comprise a pair $(s, f)$ of a function $s : S \to S'$ and a functor between the codomains $f : L \to L'$ forming an evident commutative square*. Syntactically $f : L \to L'$ maps $S$-sorted terms of $L$ to $S'$-sorted terms of $L'$. The coequaliser of two such morphisms is given by the $S'$-sorted algebraic theory $L''$ obtained by imposing equations on $L'$ that equate any two terms whose preimage under $f$ is equal. When $S = S' = 1$, this recovers the coequaliser of one-sorted algebraic theories.

(*More generally, we could take $s$ to be a function $S \to |\mathbb F(S')|$, but this definition is a little less intuitive syntactically.)