For your first question, the role of 「A には B」 is to pinpoint the location of B at A. Let's compare a direct translation alongside a version with natural sounding English:

• Direct translation: "As for (with/at/to) her, there aren't any worries"
• Natural English: "She has no worries."

The more example sentences you read that use 「には」, the more familiar and natural this will become. Here's another example:

• 「彼には弟さんがいます。」"He has a younger brother." (Lit. "At/To him, there is a younger brother.")

For your second question (please ask separately in the future instead of bundling two separate questions, thank you!) 「二番目の~」 is "the second ~" whereas 「２つの~」 is "two ~'s". Here are examples of each:

• 「二番目の選手は田中です。」"The second [place] athlete is Mr. Tanaka."
• 「２つのジャンプができました。」"He was able to do two jumps."

The role of 「A には B」 is to pinpoint the location of B at A. Let's compare a direct translation alongside a version with natural sounding English:

• Direct translation: "As for (with/at/to) her, there aren't any worries"
• Natural English: "She has no worries."

The more example sentences you read that use 「には」, the more familiar and natural this will become. Here's another example:

• 「彼には弟さんがいます。」"He has a younger brother." (Lit. "At/To him, there is a younger brother.")