"They eat an egg."
Translation:Onlar bir yumurta yerler.
For third person plural verbs, you can include the -ler/lar at the end of the verb if the action is taken by humans. It's optional and doesn't change the meaning. However this rule isn't very commonly known, so it wouldn't be a problem if you used it for non-human subjects. I hope this helps. :)
as far as I understood it:
if the last vowel in a word is one of 'a', 'ı', 'o', 'u', you append 'lar' as the suffix to signify a plural; if the last vowel in a word is one of 'e', 'i', 'ö', 'ü' you append 'ler' instead. For the verb infinitive it's 'mak' and 'mek' respectively.
For example: yapmak = 'to do'; beklemek = 'to wait'; diş = tooth (singular); dişler = teeth (plural); kemik = bone (s.); kemikler = bones (p.)
Can a native speaker confirm that that's all correct, please? :-)
Onlar bir yumurta yer.
Suffix '-ler' in 'yerler' indicates 3rd person plural. Now, Turkish language likes to omit anything that is not required for unambiguity; hence, with 'onlar' indicating 3rd person plural, verb suffix 'ler' becomes dispensable to the point that its use is optional when talking about humans (or dear pets playing a human-like role for the speaker), but considered inappropriate for any other subjects.