If your system can re-order and produce conjuncts for Indic scripts aka Brahmic scripts, then this sequence of characters:

हिन्दी should look like this image: , which says "Hindi" in Hindi.

If the sequence looks like this image instead: , your system is not re-ordering or producing conjuncts for Indic script.

To compose this word in Unicode, the characters are entered in this order:

1. ह    2. ि    3. न    4. ्    5. द    6. ी.

Unicode compatible software then:

1. "re-orders" characters 1 and 2 so 2 appears to the left of 1,
2. makes a "conjunct" (a sort of combination) of characters 3 and 4, and
3. adds the last two characters, 5 and 6.

See also Help: Multilingual support (Indic) on Wikipedia.