The Chok Yakov ( O. Ch.489) writes ,not to say the kabalistic tefilos when
counting the Omer.( Ribono Shel Olam. The Chida in Avodas Hakodesh
has a special Tefillah after each week of the Sefira.)
“The reason to refrain from these Tefilos ,is we have no clue what it means.
These tefilos are only for practicing kabalists who know and understand what they
are saying. Even the Kabalist should only say it betzina and quietly. “
Most Shuls & Kehilos do say it, so we should attempt to understand it at
least in the most elementary level.
(The Teshuvas Rashbash (189) writes that we have no clue what sefiros are.)
The Mishna in Avos
Hashem created the world Basara Ma’amoros. The Kabbalist refer to them as the ten
Sefiros , the tools with which Hashem created and runs (sends his Ha’ashpa’a ) his world.
When we say “Ma Shepagamti Bisefirah” (what I have blemished with the sefira.)
The simple explanation is, by doing an Aveirah we somehow block the Tzinor (pipe)
from where Hashem’s Ha’ashpa’a flows through to this world.