I work as a barista,  is a person, usually a coffeehouse employee
Nice, do you work at a Starbucks or a similar coffee shop?
At Starbucks@ The word "barista" is an Italian word, and in Italy, a barista is a male or female "bartender"
It must mean you have a lot of duties at work. What do you do as a barista? 
I have heard that The native plural in English is "baristas", while in Italian the plural is "baristi" for masculine
Ok, and what does a barista do? Just serve coffee?
button operation to an involved manual process. Espresso is a notoriously finicky beverage, and good manual espresso making is considered a skilled task. Further, preparation of other beverages, particularly milk-based drinks such as cappuccinos and lattes, but also non-espresso coffee such as drip or press pot, requires additional work and skill for effective frothing, pouring and most often latte art.
The barista usually has been trained to operate the machine and to prepare the coffee based on the guidelines of the roaster or shop owner,
Barista
A barista (; ; from the Italian for "bartender") is a person, usually a coffeehouse employee, who prepares and serves espresso-based coffee drinks.
Etymology and inflection.
The word "barista" comes from Italian, where it means a male or female "bartender" who typically works behind a counter, serving hot drinks (such as espresso), cold alcoholic and non-alcoholic beverages, and snacks. The native plural in English is "baristas", while in Italian the plural