All languages use essentially the same number of sounds.
This statement is true because:
All languages use a similar range of sounds: Around 40-50 distinct sounds are used in most languages, although the exact number can vary.
Human physiology limits the range of possible sounds: The human vocal tract and auditory system impose constraints on the sounds that can be produced and perceived.
The second statement is incorrect:
Native speakers typically acquire grammar rules through exposure and use, rather than formal instruction in school.
Children often develop an intuitive sense of grammar before they receive formal education.