Normally, you'd reference a note in Obsidian via the double square bracket notation:

My note refers [[Another note]].

However, you may want to add snippets inline from the [[Another note]].  This type of reference is called in Obsidian terminology transclusion. You can do it in the same way you include an image:

See this snippet:

![[Another note]]

Example

If you have a note with the following content:

---
filename:first note
---

# About

This is the first note and it's important

And a second note:

---
filename: second note
---

# About

This a note that references [[first note]] inline like so:

![[first note]]

The end result ( in preview mode) would look like this:

How cool is that?

What's even cooler, is that you can include a single section if you want. If you have:

---
filename: second note
---

# About

This a note that references [[first note]] inline like so:

![[first note#About]]

(note the "#About" in the inline link), then you get:

HTH,