I don't understand this logic with StockHistory function...

There's no logic with STOCKHISTORY. The function pulls information, that's it. The logic you describe is yours

Assuming you want to pull the last 10 days history for each stock/symbol in E4# and keep/display only the last day, one option:

in F4:

=LET(
  end_date,   TODAY(),
  start_date, end_date -10,
  BYROW( E4#, LAMBDA(symbol,
    TAKE( STOCKHISTORY( symbol, start_date, end_date,, 0, 1 ), -1 )
    )
  )
)