Vowel dropping is integral to the art of the Russian plural. Absolutely integral. If you don't learn it - well - let me begin by saying I am a haunted man. I can see her - always - Madam Lyudmila, tapping her 24-inch ruler on her thigh, wincing at my pronunciation. Let us begin.
To form the Russian plural (and I'm simplifying, and also transliterating Cyrillic from English), you usually add "i" or "iy" to your noun. Therefore, "malchik" (boy) becomes "malchiki" (boys).
Very simple. No, it's not. It will stalk you and curse at you from behind shrubs for the rest of your life until you regret ever learning Russian as a second language - you try to form the plural as Madam Lyudmila watches, keenly now - and she's tapping her ruler again - faster this time - and squinting at you with those cold - oh, those cold eyes of hers. No, Maksim (says she) try again.
No, Maksim (says she) you must drop the vowel (and those eyes again - well, she's right).
In addition to the multitude of other rules governing plurals, certain masculine nouns drop certain vowels when the plural is formed. For example, the word for "father" is "otyets." So the plural would be "otyetsi," right? Nope. It's "otsi," dropping the "ye." ("Ye" in Russian is one letter.) Similarly, the word "amerikanyets" is "amerikantsi" in plural.
Why is this? My guess is that it probably originated with Russians saying these words quickly - "otyetsi" became "otsi" et cetera, much the way the patronymic "Ivanovich" is often pronounced coloquially as "Ivanyich."
That (says Madam Lyudmila - smiling) is the mystery of the Russian language.
That (says I) is probably why you killed your governess with a fork.