A vowel /e/ appears in the first syllable of many Mi’gmaq verbs.  You will notice that this /e/ goes missing in lots of related words.

teli’si                    I speak (that) way
tli’si                    speak (that) way!
tli’sites                I will speak (that) way
tli’suti                    language (way of speaking)

This /e/ comes in mostly for events that are real: they are actually happening, or they did.  This is why they’re not used for commands or for the future, since haven’t actually happened yet.  It is also pretty consistently not used for most related nouns (like tli’suti ‘language’ here), and verbs made directly/recently from nouns.

What’s more, this /e/ only comes in on words whose first syllable has the weak vowel /’/.  Where the /e/ is not used, you get the original weak vowel form.  But most often that weak vowel is actually dropped or left unwrittten.  That lost vowel is why the /e/-less forms start with two consonants in a row, like /tl/ up above.

You will be understood most of the time if you mix up when to use the /e/-forms and when not to, but it does sound like a kid saying “I sleeped all night”.  For the start, just learn to recognize it when it happens—“Oh, that had the /e/, and that didn’t”—and pretty soon you will pick up the pattern automatically.