The letter र (r) is combined specially with other letters. If the simbol is above the letter, it means you pronounce the 'r' sound before the letter. If the simbol is below, your pronounce it after. Examples: र् + क = र्क as in ''sark'' सर्क
क् + र = क्र as in ''cross'' क्राॅस
Another related letter is ऋ (ri). When combined with another letter it looks like this:
कृपया (kripya = please,kindly).