What is the meaning of .sn?

The ccTLD for Senegal as assigned by the IANA.

they, them, their (see usage notes)

Only when attached to a dual noun or prospective participle.

Only when attached to a dual noun or prospective participle.

Only in formal texts, especially religious texts.

Only in postclassical (Neo-Middle Egyptian) texts.

Only in formal texts, especially religious texts.

Source: wiktionary.org