Complex sentence: On the other hand, Black usually will not be able to develop the queen bishop without first giving up the center with... dxc4, developing the bishop may leave the black queenside weak, and the thematic break... c5 incurs the loss of a tempo.
Split into simpler sentences: On the other hand, Black usually will not be able to develop the queen bishop without first giving up the center with... dxc4, and developing this bishop may leave the black queenside weak. Additionally, the thematic break... c5 incurs the loss of a tempo.