Yes, 2nd Display Support:Dual/Mirroring*2nd Max. Resolution:2560x1600 (x2)
Details:*This model can simultaneously support two external displays up to 2560x1600 via Thunderbolt.
This model is equipped with two Thunderbolt ports. Thunderbolt is backwards-compatible with Mini DisplayPort-equipped displays as well as adapters that are compatible with Mini DisplayPort (DVI, VGA, dual-link DVI and HDMI). It also can support other peripherals that use the Thunderbolt standard, which provides a maximum theoretical 10 Gbps of bandwidth in both directions.
https://everymac.com/systems/apple/imac/specs/imac-core-i3-3.3-21-inch-aluminum-early-2013-education-specs.html#macspecs2
So it depends what inputs are on the Monitor, so MDP to HDMI or such. :)