The noun ending -kor is used to express "at ... time". It may be added to the cardinal number or the word for hour:

• Találkoztunk négykor We met at four (o'clock)
• Találkoztunk négy órákor We met at four o'clock

Of course, -kor can apply to the demonstrative pronouns too, to give:

• az + -kor = akkor at that time
• ez + -kor = ekkor at this time

Akkor (at that time) is used as "then":

Mikor hazamesz? Akkor látlak.
When are you coming home? I'll see you then. (When home-you-come? At-that-time I-see-you)

Amikor Budapesten reggel 8 óra van, akkor Londonban még csak 7 óra van. When in Budapest it's 8 in the morning, then in London it's still just 7.
Amikor New Yorkban reggel 7 akkor Szófiában már 14:00 van. When in New York it's 7 in the morning, then in Sofia it's already 14:00.

This ending can also be used to mean an era or an epoch. The most obvious is gyerekkor - childhood.

Gyerekkoromban, nem voltam kövér. In my childhood, I was not fat.

Gyerek-kor-om-ban: child-era-my-in.