hakgyo motungie kapega isseoyo.

-에 is the location particle that marks where something exists. With the existence verb 있다, you always use -에 to indicate “at” or “in.”
Example: 학교 모퉁이에 = at the corner of the school.

• 에서 marks the location where an action takes place (e.g., 공원에서 운동해요 = “I exercise at the park”).
• Existence verbs (있다/없다) do not describe an action, so they use -에 for location.
  Thus, 카페가 있어요 always takes 모퉁이에, not 모퉁이에서.

• 이/가 often introduces or points out new information; existence statements typically use the subject marker to say “there is/are X.”
• 카페가 있어요 = “There is a café.”
• You can use 카페는 if you want to contrast or make it the topic, but then it changes the nuance:
  • 카페가 있어요: Simply stating the café exists.
  • 카페는 있어요: “As for the café… it does exist (but maybe other things don’t).”

Korean has speech levels:
• 있어 = casual/informal (friends, kids)
• 있어요 = polite/informal (general polite speech)
• 있습니다 = polite/formal (announcements, presentations)
Here we use the common polite ending -아요/어요, so 있어요.

Korean doesn’t use articles. Context tells you if it’s definite or indefinite.
• 카페가 있어요 can mean “There’s a café” or “There’s the café” depending on what you’ve been talking about.