This is the 8578th most frequent Spanish word.
sem
"Sem" is not a recognized standalone word in Spanish. It may be a fragment or abbreviation.
Here, 'sem' appears to be a misuse or variant of 'soy,' which is the correct verb form in standard Spanish for the first person singular.
Yo sem siempre el primero en llegar a clase.
I am always the first to arrive to class.
In this instance, 'sem' could be interpreted as an erroneous substitute for 'tendré,' the future tense of 'tener' (to have).
Este domingo sem mucho tiempo libre para pasear.
This Sunday I will have plenty of free time to go for a walk.
This sentence uses 'sem' as a noun, treating it as an independent term. It could be related to a non-standard or colloquial usage.