England have struggled to score in every game. One reason being that Kane is not really fit, and he has to keep dropping into midfield to pick up the ball. England's play is also very ponderous and conservative, so chances have been at a premium. Sterling has scored 3 in 4 games but he is another player who ended the season in mediocre form, and aside from his goals has made quite a few errors in his general play and holds onto the ball for too long.
They should have enough to beat Ukraine by a couple but don't let the clean sheets fool you too much, even though they are pretty defensive they still look like conceding goals when put under any pressure. Germany cut through them a few times with wide open gaps, but they haven't really played against any quality players aside from that game, and may not again until the final, were they to reach it.