Translation:The child plays the lyre and sings.
Σ'ευχαριστώ πολύ! That's actually what I wrote originally, but when I researched the construction, I fell under the impression that we are supposed to drop the σίγμα τελικό from proper masculine nouns in such occasions.
Is it indeed sometimes omitted and if so, when do we do that?
In this phrase you have (correctly) used the nominative: ο νεαρός Ορφέας. Why would you drop the ς just from the noun? ;)
The ς is dropped in all other cases (declensions) from masculine nouns, proper or not, and masculine adjectives, but the exact ending depends on the category of the noun/adjective.
There are tables showing how each category declines, for example see here: https://en.wikipedia.org/wiki/Modern_Greek_grammar#Declensions. You can also check wiktionary, usually there is a declension table available.
Alternatively, you can find more extensive tables in grammar books, such as the one currently taught in Greek schools http://ebooks.edu.gr/modules/ebook/show.php/DSGYM-A112/621/4006,17971/
In the drop down menu on the top right hand corner 2. Τα Ουσιαστικά is the nouns and 3. Τα Επίθετα is the adjectives. While the book itself might not be of much help at this point as it is all in Greek, you could copy and paste the tables in a word document (I just tried it in MS Word and the formatting luckily remains intact!) to refer to when unsure. After each table, the text gives examples of other words falling the same category.
It was actually wrong (ο νεαρός Ορφέα), but I edited it after your first comment, so people won't see puns in bad Greek at the top.
Thanks for your extensive reply! Yes, it really doesn't make much sense to drop the ς just from the noun when you put it that way, what was I thinking!? Now I will definitely remember it. :)
Otherwise, your links are golden! Looking up conjugation tables is definitely the proper thing to do in such cases, instead of inferring from usage patterns on random websites (where the author may have missed a letter or just be another Greek learner, etc, etc).
I can't understand everything in the book yet, but we have studied enough Greek in the course to extract a surprisingly large amount of useful information from it, so I am bookmarking it. Kudos to the Greek team for including grammar vocabulary in the course. I was struggling to remember it, but it is quite helpful now! :)