It's red wine, Barbera is the name of the grapes and d'Alba means from Alba, a city. The wine is made in this part of Piedmont.
Wines from Barbera d'Alba
It's not very expensive, but still people like it.
I can't tell you exactly what it tastes like as I haven't been drinking any wine for years.
The two dots above the vowel, ö in this case are not mandatory, at least not in Italian. Unlike in German they're not Umlauts. They just point out that there is a pause between the two vowels.
It's kind of rare in English.
Examples:
Citroën - Citro - en
Caöda - Ca - oda
Mariä - Mari - a