你应该多跟中国人谈话。( you should more conversation with chinese people.) 你应该多跟中国人话。 ( you should speak more with chinese people) 你应该多跟中国人谈。( you should more discuss/ talk with chinese people)

Thanks a lot for your clear reply!

谈话 and 谈 is correct because both are verb。 in your second sentence you should write 说话 instead of 话。 Because 话 is noun here, and it means words. speech, sayings and language. but your second sentence need a verb to complete the sentence so using 说话 will be more appropriate.

is your mean 谈话 and 谈 are wrong?

跟中国人话 is incorrect！！