What does "shielding of A" mean?
1) Protection from A
2) Protection of A from something else
Examples from web:
1) EMF 70 is a premium precious metal window film for shielding of windows and glass surfaces from high-frequency radiation (HF).
2) NEW-DAYLITE™ from Swiss-Shield® is a highly-transparent Trevira® fabric for the shielding of high-frequency electromagnetic fields (HF).
Are both correct?
“The shielding of A” most commonly means protecting A from something (that is, your option 2).
For example, “The shielding of your barbecue from the weather with a fabric cover, roofing, etc. will prolong its useful life.”
However, you have also identified how constructions like, “the shielding of weather from your barbecue” are possible. As a learner, I would not recommend that you use “shielding” in this unusual way. It is correct but it is not idiomatic.
Shielding can be applied either to what is protected from some influence or to the source of that influence (if not to both).
Example 1 is about protecting A (by shielding it) from something else.
Example 2 is about isolating A (by shielding it as a source of an undesirable influence) from everything else (which is thus protected).
