These were the trials for the 1988 Olympics in Seoul, Korea. (Para.3)
Meaning: These were a sequence of matches for the 1988 Olympics in Seoul, Korea.
Please note that the word "trial" is a special term for sports here. When it is used in this sense it is often used in the plural form. However, "trial" is often used in the following sense.
trial: n. 1) (an act of) testing to find quality, value, or usefulness
The trials show that the medicine is safe for most people. 实验表明这种药对大多数人而言都是安全的。
2) (an act of) hearing and judging a person or case in a court
After the trial they could meet their relatives. 审判之后他们可以同亲属见面。