Preparing Nd2-b3 in order to seize the protected square on c5. This is the best way to do it, since the temporary attack on the c6-pawn limits Black's replies.
By recapturing this way White keeps the c5-square under control and facilitates the attack on the c6-pawn.
With the threat of 11 Re8. Thanks to his control of the open file White is clearly better.
By exploiting a simple tactical detail White manages to seize the c-file.