To view columns in a table, use SHOW COLUMNS.

%sql
show columns in <schema_name>.<table_name>

To show all the tables in a column, use following PySpark code:

%python
 
schema_name = "default"
tbl_columns = {}
 
# Get all tables in a schema
tables = spark.sql("show tables from {}".format(schema_name)).\
               select('tableName').\
               rdd.map(lambda x : x[0]).\
               collect()
 
 # Get all columns in each table
for table in tables:
  tbl_columns[table]=spark.sql("show columns from {}.{}".format(schema_name,table)).\
              select('col_name').\
              rdd.map(lambda x : x[0]).\
              collect()
 
print(tbl_columns) #print JSON