Language delay is a failure to develop language abilities on the usual developmental timetable.
If your child does not seem to be meeting communication milestones, talk to a speech therapist. It may be nothing, but if your child is delayed in some way, recognizing and treating the problem early is crucial for developing language and learning skills in the long run.
Keep in mind that the timetable for language development is broad, and each child develops at his/her own pace.
But as a general rule, trust your instincts. If something seems wrong to you, call a speech therapist. After all, you know your child best. If your child does have a problem, therapy should begin as soon as possible. Early intervention is important because the first few months of a child’s life are vital to the development of language and communication skills and we must take advantage of this period of normal brain development. This will greatly improve the child's ultimate outcome.