Text copied from Wikipedia :
In many abugidas, there is also a diacritic to suppress the inherent vowel, yielding the bare consonant. In Devanagari, क् is k, and ल् is l. This is called the virāma or halantam in Sanskrit. It may be used to form consonant clusters, or to indicate that a consonant occurs at the end of a word. In Sanskrit, thus, a default vowel consonant such as क does not take on a final consonant sound. Instead, it keeps its vowel. For writing two consonants without a vowel in between, instead of using diacritics on the first consonant to remove its vowel, another popular method of special conjunct forms is used in which two or more consonant characters are merged to express a cluster, such as Devanagari: क्ल kla. (Note that on some fonts display this as क् followed by ल, rather than forming a conjunct. This expedient is used by ISCII and South Asian scripts of Unicode.) Thus a closed syllable such as kal requires two aksharas to write.
Does that mean that the Devanagari क्ल kla is formed by one akshara and कल् kal requires two aksharas ?