instituto

No suffix here, and the false one is tempting. The word ends in what looks like a piece of machinery: instru- is a real root (instrui, to teach), and Esperanto is full of productive affixes, so the eye wants to cut institut- into parts. Do not. There is no -ut- suffix in Esperanto at all - the official list has -ul-, -uj-, -um- and nothing between them - and institut- is a single borrowed unit from Latin. It is not instrui plus anything, and the resemblance is coincidence: instrui comes from instruere (to build into, to equip), instituto from instituere (to set up). Neighbours in the Latin dictionary, not relatives in Esperanto.

What it names. An instituto is a formal body set up for research or teaching, usually smaller and more specialised than a universitato: a research instituto, a language instituto, an instituto inside a larger university. The Esperanto movement's own institutions use it constantly, so it is a word you meet early in the organisational vocabulary alongside asocio, societo and kongreso.

The verb is not derived from it. Institui exists and means to institute or establish, but the everyday verb for setting one up is fondi, to found. Oni fondis la instituton is what a normal sentence says.