This paper demonstrates the implementation of a sub-millisecond iSWAP gate between individually trapped $X^+ \Sigma^+$ NaCs molecules, a significant step towards universal quantum computing with trapped polar molecules. The authors leverage the intrinsic dipolar interaction between rotational states of the molecules to create a two-qubit Bell state with a fidelity of 94(3)%. They characterize the dipolar interaction by measuring the entanglement fidelity of a Bell state, finding that decoherence is primarily due to molecular motion along the axial trapping direction, with a ground state fraction of 32(5)%. The interaction is toggled by transferring between interacting and non-interacting hyperfine states, allowing the encoding of qubits in a non-interacting subspace. The truth table of the iSWAP gate is verified, showing a fidelity of 0.92+0.05−0.09. The gate performance is limited by leakage during hyperfine-state transfers and interactions during toggling pulses, but future improvements are expected through better microwave polarization control and reduction of single-molecule dephasing. The results establish trapped polar molecules as a viable platform for universal quantum computation and advanced quantum simulations.This paper demonstrates the implementation of a sub-millisecond iSWAP gate between individually trapped $X^+ \Sigma^+$ NaCs molecules, a significant step towards universal quantum computing with trapped polar molecules. The authors leverage the intrinsic dipolar interaction between rotational states of the molecules to create a two-qubit Bell state with a fidelity of 94(3)%. They characterize the dipolar interaction by measuring the entanglement fidelity of a Bell state, finding that decoherence is primarily due to molecular motion along the axial trapping direction, with a ground state fraction of 32(5)%. The interaction is toggled by transferring between interacting and non-interacting hyperfine states, allowing the encoding of qubits in a non-interacting subspace. The truth table of the iSWAP gate is verified, showing a fidelity of 0.92+0.05−0.09. The gate performance is limited by leakage during hyperfine-state transfers and interactions during toggling pulses, but future improvements are expected through better microwave polarization control and reduction of single-molecule dephasing. The results establish trapped polar molecules as a viable platform for universal quantum computation and advanced quantum simulations.