An is a type of Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese drinking establishment

Bar (establishment)

A bar is a business establishment that serves alcoholic drinks — beer, wine, liquor, and cocktails — for consumption on the premises.Bars provide stools or chairs that are placed at tables or counters for their patrons. Some bars have entertainment on a stage, such as a live band, comedians, go-go...

 which also serves food to accompany the drinks. They are popular, casual places for after-work drinking.
The name "izakaya" is a compound word consisting of "i" (to stay) and "sakaya" (sake shop), indicating that izakaya originated from sake shops that allowed customers to sit at the premises to drink.

Izakaya are sometimes called akachōchin (red lantern

Lantern

A lantern is a portable lighting device or mounted light fixture used to illuminate broad areas. Lanterns may also be used for signaling, as 'torches', or as general light sources outdoors . Low light level varieties are used for decoration. The term "lantern" is also used more generically to...

) in daily conversation, because these paper lantern

Paper lantern

Paper lanterns come in various shapes and sizes, as well as various methods of construction. In their simplest form, they are simply a paper bag with a candle placed inside, although more complicated lanterns consist of a collapsible bamboo or metal frame of hoops covered with tough paper.-In Asian...

s are traditionally found in front of an izakaya.
Depending on the izakaya, customers sit on tatami

Tatami

A is a type of mat used as a flooring material in traditional Japanese-style rooms. Traditionally made of rice straw to form the core , with a covering of woven soft rush straw, tatami are made in standard sizes, with the length exactly twice the width...

 mats and dine from low tables in the traditional Japanese style, or sit on chairs and drink/dine from tables.