The more slowly and distinctly you speak, the more easily non-native English speakers will be able to understand you. Use pauses to let them digest what you have said and form responses. The style of speaking can also help. Keep the tone calm and respectful. It is all right to emphasize key words, but consistent use of oversimplified, gramatically incorrect English may insult the listener's intelligence.
Visual aids can give the worker more ways to understand.
Pictures, charts, and diagrams are all good bridge-builders. So is the written word. Writing down instructions or key ideas from meetings and phone calls gives ESL employees greater opportunity to grasp information fully. Supervisors are often frustrated when ESL workers indicate they understand instructions, when in truth they do not. Because they do not want to look foolish, or to insult you by implying that you have not explained well enough.