In the English language, vowels can be short or long.
* Short vowels have a quick, clipped sound (like the "a" in "cat" or the "e" in "bed").
* Long vowels have a drawn-out sound (like the "a" in "cake" or the "e" in "see").
The "tail" you're referring to are often silent "e"s at the end of a word. They are called silent "e"s because they don't make a sound, but their presence often indicates that the preceding vowel has a long sound.
Here are some examples:
* cat (short "a") vs. cake (long "a")
* bed (short "e") vs. bee (long "e")
* hop (short "o") vs. hope (long "o")
It's important to note that:
* Not all long vowels have a silent "e" at the end.
* Some words have long vowels that are spelled with double vowels (like "moon" or "food").
Let me know if you have other questions about vowel sounds or spelling!