Minor corrections in variables_and_subexpressions.md (#906)

Author: mrkkrp

book/variables_and_subexpressions.md

@@ -122,7 +122,7 @@ We can use a variable path to evaluate the variable `$my_value` and get the valu
 testuser
 ```
 
-Sometimes, we don't really know the contents of a variable. Accessing values as shown above can result to errors if the path used does not exist. To more robustly handle this, we can use the question mark operator to return `null` in case the path does not exist, instead of an error, then we would write custom logic to handle the `null`.
+Sometimes, we don't really know the contents of a variable. Accessing values as shown above can result in errors if the path used does not exist. To more robustly handle this, we can use the question mark operator to return `null` in case the path does not exist, instead of an error, then we would write custom logic to handle the `null`.
 
 For example, here, if row `0` does not exist on `name`, then `null` is returned. Without the question mark operator, an error would have been raised instead
 
@@ -144,11 +144,11 @@ You can always evaluate a subexpression and use its result by wrapping the expre
 
 The parentheses contain a pipeline that will run to completion, and the resulting value will then be used. For example, `(ls)` would run the [`ls`](/commands/docs/ls.md) command and give back the resulting table and `(git branch --show-current)` runs the external git command and returns a string with the name of the current branch. You can also use parentheses to run math expressions like `(2 + 3)`.
 
-Subexpressions can also be pipelines and not just single commands. If we wanted to get a list of filenames larger than ten kilobytes, we can use an subexpression to run a pipeline and assign the result to a variable:
+Subexpressions can also be pipelines and not just single commands. If we wanted to get a table of files larger than ten kilobytes, we could use a subexpression to run a pipeline and assign its result to a variable:
 
 ```
-> let names_of_big_files = (ls | where size > 10kb)
-> $names_of_big_files
+> let big_files = (ls | where size > 10kb)
+> $big_files
 ───┬────────────┬──────┬──────────┬──────────────
  # │    name    │ type │   size   │   modified
 ───┼────────────┼──────┼──────────┼──────────────
@@ -175,7 +175,7 @@ It depends on the needs of the code and your particular style which form works b
 
 ## Short-hand subexpressions (row conditions)
 
-Nushell supports accessing columns in a subexpression using a simple short-hand. You may have already used this functionality before. If, for example, we wanted to only see rows from [`ls`](/commands/docs/ls.md) where the entry is at least ten kilobytes we can write:
+Nushell supports accessing columns in a subexpression using a simple short-hand. You may have already used this functionality before. If, for example, we wanted to only see rows from [`ls`](/commands/docs/ls.md) where the entry is at least ten kilobytes we could write:
 
 ```
 > ls | where size > 10kb
@@ -189,4 +189,4 @@ The `where size > 10kb` is a command with two parts: the command name [`where`](
 > ls | where {|$x| $x.size > 10kb }
 ```
 
-For short-hand syntax to work, the column name must appear on the left-hand side of the operation (like `size` in `size > 10kb`).
+For the short-hand syntax to work, the column name must appear on the left-hand side of the operation (like `size` in `size > 10kb`).