"He designs dresses."

Translation: O elbise tasarlar.

[leighozdemir]

Why is it tasarLAR? Is this an irregular verb?

[AlexinNotTurkey]

The verb root is "tasarlamak" :) Ergo, "tasrala+R" = "tasarlar." The plural of this would be tasarlarlar.

[AyaA2]

What about elbiseleri or elbiseler ?

[ex_contributor]

no, that doesn't work in Turkish, general (i.e. indefinite) objectss are almost always in singular https://www.duolingo.com/comment/7736911

[AyaA2]

Sağolun :)))..

[pooneh5310]

Elbise in answer is singular but in the question plural wants

[Amin.mq]

Selcen has sent a good reference in comments above, just to make it more clear :

In English dresses addresses a general dress, not specific one ( she generally designs dresses, any dress)

In Turkish to make something general you don't need to follow the same rule of English, you just need to say it singular without any suffix. Elbise.

Note: by adding accusative suffix, you simply change it to specific object (o elbiseyi tasarlar = she designs the dress)