What is the Zuzana howitzer Slovakia is sending to Ukraine?

In April, Slovakia donated its Soviet-era S-300 air defence system to Ukraine.

In return, Washington sent US Patriot missiles to replace them, with Germany and the Netherlands sending Patriot batteries and troops to Slovakia.

Despite being a small country, Slovakia has provided relatively large amounts of military aid to Ukraine, including five helicopters, 30 T-72 tanks, ammunition for the BM-21 Grad multiple launch rocket system and 11 MiG-29 Fulcrum fighters.

Now, Slovakia is set to send Zuzana 2 155mm self-propelled howitzers to Ukraine – but what is the weapon and how will it benefit Ukrainian armed forces?