tel / tell are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
tel: NA
tell: (noun) a Swiss patriot who lived in the early 14th century and who was renowned for his skill as an archer; according to legend an Austrian governor compelled him to shoot an apple from his son's head with his crossbow (which he did successfully without mishap). (verb) let something be known. (verb) narrate or give a detailed account of. (verb) discern or comprehend. (verb) give evidence.
tel: t·EH·l
tell: t·EH·l
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)