The Korean written language is properly called Hangul, although its English spelling is not always identical across sources.
Korean was written with Chinese characters, but this was replaced by the hangul alphabet. Both the old logographic system and the newer phonetic system are in use in Korea today, however hangul is predominant in everyday usage.
One who learns Hangul's phonetic alphabet might sound out printed words without the least understanding of their content. As an amusement, one might write English sentences using Hangul's phonetic alphabet.
There are two counting systems in Hangul, the native counting system and a system borrowed from Chinese. They are used for enumerating different things. For comparison, think of the English cardinals "one, two, three,...", ordinals "first, second, third,..." and prefixes "uni-, bi-, tri-,...".
The native counting system is used for counting among others things, people, furniture, meals and hours.
The Sino-Korean system is used commonly for measurements, such as metres, seconds, minutes, money and floors (in a building).
Vowels are pronounced roughly as in Spanish, except the combination "eo" is pronounced like "u" in "fun." The "l" at the end of words is non-velarized.