All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Wearing a dress which has writings on it depends on what is written, if the writings are something glorified in Islam, like the Quran, Prophetic narrations, the Names and Attributes of Allaah, and the names of the Prophets and angels, and the like, then it is not permissible to wear it as it is subjected to humiliation because of the sweat and other dirt to which the dress is subjected. Undoubtedly, wearing a dress and sweating in it contradicts glorifying what is written on it. Rather, such writings must be protected from anything which is contradictory to glorifying it or subjecting it to humiliation. Allaah Says (what means): {That [has been commanded], and whoever honors the sacred ordinances of Allaah — it is best for him in the sight of his Lord.}[Quran 22:30]. Allaah also Says (what means): {That [is so]. And whoever honors the symbols [i.e. rites] of Allaah — indeed, it is from the piety of hearts.}[Quran 22:32].
Moreover, one should not wear clothes on which the Arabic language is written, even if what is written is not something that is glorified in religion, because the Arabic alphabet is sacred, as stated by the scholars due to the fact that the Quran was revealed with its letters.
However, if what is written on the clothes is in a language other than Arabic, and it is not obscene language or propagates falsehood, then in principle it is permissible to wear it. Nonetheless, it is better to avoid wearing such clothes according to the view that all letters, even in a language other than Arabic, are sacred because other revelations could have been revealed using such alphabets.
Allaah Knows best.