Schneider Electric S.E. (SU.PA) PAR - Schneider's listing on the Euronext Paris exchange.
Schneider Electric S.E. (SBGSF) PNK - This is an "F share" (the 5-letter ticker ends with "F"). US broker-dealers created this ticker to provide US investors with quotes of Schneider in US dollars instead of Euros. This represents US over-the-counter market quotes of Schneider's Euronext Paris shares. More details about F shares: FAQ on F Shares - OTC Markets
Schneider Electric S.E. (SBGSY) PNK - This is an American Depositary Receipt (ADR), as evidenced by its 5-letter ticker that ends with "Y". This represents Schneider's unsponsored ADR traded on the US over-the-counter markets. If you're not familiar with ADRs, read: American Depositary Receipt – ADR
What does "PNK" mean?
"PNK" is short for Pink Sheets. This is the US over-the-counter (OTC) market for stocks I mentioned above. Beware of potential liquidity issues and extra brokerage fees when trading OTC securities.
Which should you choose? If you are able to buy securities listed on the Euronext Paris exchange, you should choose "SU.PA" over the others, because it is the official listing and has the highest liquidity.