Hyfryd y tywydd yma "The weather here is lovely"
Cymry y dynion yno "The people over there are Welsh"
In the above examples you'd use the
yw.
Occasionally you come across the
yw in phrases and proverbs that reflect a more archaic style, e.g.
Cenedl heb iaith, cenedl heb galon "A nation without a language
is a nation without a heart" or
Nid aur popeth melyn "Not everything that's yellow
is gold" (i.e. "All that glitters is not gold"), although you're probably more likely to hear some of them with the copula these days, e.g.
Nid aur yw popeth melyn.
Wikipedia mentions the zero-copula construction was popular in poetry in the past.
It also mentions the possibility of zero copula with the reduplicated pronouns, which you may or not be familiar with.
mi,
fi,
i >
minnau,
finnau,
innau
ti >
tithau
ef,
fe,
fo >
yntau,
fyntau
hi >
hithau
ni >
ninnau
chwi,
chi >
chwithau,
chithau
hwy,
nhw >
hwythau,
nhwthau
They're usually used with the meaning "... too".
A:
Sut wyt ti? "How are you?"
B:
Iawn, diolch. A tithe? "Fine, thanks. And you?"
A:
Mwynhewch y penwythnos! "Have a good weekend!"
B:
A chitha! "You too!"
But they can also be used with
a "and" in zero-copula phrases, such as:
A hithau'n 150 mlynedd ers sefydlu gwladfa Patagonia, beth am i ni neidio mewn bws o'r enw Mimosa a gyrru i'r Alban?
"With it being 150 years since the founding of the colony in Patagonia, what about we jump in a bus called
Mimosa and drive to Scotland?"
A hithau'n Ddiwrnod y Ddaear heddiw rydyn ni'n edrych ymlaen at lansio Cyfres Wenfro gan Llinos Mair
"What with it being Earth Day today we're looking forward to launching the Wenfro Series by Llinos Mair"
Bydd Hefina Pritchard yn coginio cyri i Dylan Jones a hithau'n Wythnos Genedlaethol Cyri!
"Hefina Pritchard will be cooking curry for Dylan Jones as it's National Curry Week!"
A ninnau'n cofio canmlwyddiant dechrau'r Rhyfel Byd Cyntaf, bydd rhifyn arbennig o'r raglen
"As we're remembering the centenary of the start of the First World War, there will be a special edition of the programme"
A Chithau'n Feichiog: Sut i Osgoi Heintiad o Fwyd ac o Gyswllt ag Anifeiliaid
"While You Are Pregnant : How to Avoid Infection from Food and from Contact With Animals"
So I guess I'd translate it "(what) with ... -ing" or "while/as ...". In fact, I think a similar construction in Cornish is their only way of expressing "while" e.g.
ha hi ow kana = a hithau'n canu. It's a nice little way to make your Welsh a bit more idiomatic now and then.