"Red and white are the colours of the flag of England."
Translation:Coch a gwyn yw lliw baner Lloegr.
I remember reading a note that mentioned that things are left in the singular, maybe in the numbers section? For example they would say ten cat (deg cath) instead of ten cats
It sounded wrong to me so I have just checked with a native speaker and he agrees too. 'Coch a gwyn yw lliwiau' sounds much better even if 'Coch a gwyn yw lliw' is correct in some obscure grammatical way.
Why can you not start the sentence with mae? I wrote mae coch y gwyn yn y lliwiau baner Lloegr.
I don't know how to explain it in proper grammatical terms but in Welsh you use different constructions when you say 'what something is' to when you describe something with an adjective or use a verb to talk about what this thing (or person) is doing.
Consider Athro dw i - I'm a teacher Dw i'n hapus - I'm happy Dwi'n dysgu - I'm studying
Lliwiau yw gwyn a choch - White and red are colours Mae coch a gwyn yn hyfryd - Red and white are lovely Mae coch a gwyn yn cymysgu yn dda - Red and white are mixing well