Learn English – When should I use fatherland instead of motherland

Using speak, tell, say, and talk is a very common problem for ELL.

@Siddhartha and @Em1 gave great answers, so let me quickly list only those aspects not mentioned by them.

So, I have some meaning to convey. How do I know which word to use?

• Ability — if it's about ability, "talk" is preferred: "cats can't talk", "when I'm drunk I lose my ability to talk". Note that "speak" is allowed but is less popular;
• Languages — use "speak": "I speak English";
• Action — covered in answers above; both words can be used; "speak" is mostly about single-direction, while "talk" usually refers a conversation (and is less formal);
• Express information — use "say" or "tell": "I told her that I love her". Here, "I love her" is the information being expressed. "Say" can also be used, but it connotates a single-time action. Compare: "I said that the discussion is over and hung up the phone."

Consider this sentence:

I can see they are talking, but I don't know what they are saying.

Here, you see an action, but you don't know or don't understand the meaning of the information others are exchanging.

• Wide topic, narrow topic:
  • use "say" or "tell" if the topic is narrow or it's about a small piece of information: "I told her there is a party tonight";
  • use "talk about" or "speak about" when the topic is wide: "We are speaking about history". There's also an idiomatic construct, "talk politics" that omits "about".
• Conversing during an extended period of time: use "talk about" or "speak about", as above;
• Imperative usually follows the rules above, but due to an extended popularity, here's a brief:
  • Extended time or dialogue — "Talk to me."
  • Long monologue — "Tell me about your problem."
  • Short monologue — "Say something!"
  • Requesting a certain attribute of speaking process — "Speak slowly please."

First, when you say:

German-American

it means your *ethnic" background is German (meaning your ancestors at some time were from Germany), but you were born in America. Or you were born in Germany but now permanantly residing in America.
This should apply to any nation specific usage.

As for:

African-American

this is more general. It could be like "European-American".

Such a person (or their ancestors) would be (or would be perceived to be) from that region of the world. I think we all know the general criteria used, but that is another discussion.