Do I have to provide information about the number of foreign stock that I own or their market value?
You may have to declare the account in which you hold the stocks (such as a brokerage account) if it is located outside the United States and your total non-US financial holdings are over the threshold required to file Form 8938.
You do not, however, have to report the actual stock holdings that you hold.
If you sell stocks, the sales do have to be reported on your tax return.
If you own more than 10% of a foreign company (i.e. probably a private company) it must be reported on the Form 8938.