First you should observe whether your child's hearing abilities for are normal or not. For this you should consult a speech therapist first he will evaluate his hearing capabilities, and if if the hearing is normal then you may be rest assured, as it could be a simple physiological delay in speech development,, which gets corrected on its own as the child grows. On the other hand if his hearing is subnormal  then and he requires specific therapy for that.

Your baby seems Oki but language development is dependent on parents and families environment 1.. talk him more 2...don’t show him mobile phones 3...don’t watch TV in front of him upto 4 year of age ...4 ...facial expression to him for word spellings 5...proper nutrition

40 to 50 words is ok at this age.Parents should give adequate time. Encourage the child to communicate verbally.All family members should   talk with the child as much as possible

Development of speech is variable. It may take upto 4 years age. If he understands everything then hearing seems to be normal.

Speech can sometimes be normal. Keep talking to him as much as you can & throw new vocabulary every day. Is his hearing normal?? If not, then get an evaluation done ( BERA)

Does he form short sentences? The more you talk to him, the more he will develop speech. Avoid mobile and laptop. Reduce screan time. You yourself enact the storys and rhymes. Start singing and involve him. Speech is also a learning skill.

It requires detailed evaluation because the causes are broad. Your toddler’s vocabulary should increase (to too many words to count) and he or she should routinely combine three or more words into sentences. Comprehension also should increase — by 3 years of age, a child should begin to understand what it means to “put it on the table” or “put it under the bed.” Your child also should begin to identify colors and comprehend descriptive concepts (big versus little, for example) Spend a lot of time communicating with your child, even during infancy — talk, sing, and encourage imitation of sounds and gestures. Read to your child Use everyday situations to reinforce your child’s speech and language. In other words, talk your way through the day. For example, name foods at the grocery store, explain what you’re doing as you cook a meal or clean a room, point out objects around the house, and as you drive, point out sounds you hear. Ask questions and acknowledge your child’s responses (even when they’re hard to understand). Keep things simple, but never use “baby talk.”

Though 40 to 50 words is on the lesser side it is not alarming..since he has started to speak make him feel he has to express himself only by words..speak to him in a single language and decrease sfreentime.you can wait for 3 more months to see his improvement